When users experience slowness in Gmail, these advanced troubleshooting steps can help administrators diagnose users' connections. Users can conduct a number of troubleshooting steps themselves by following the corresponding procedures for user troubleshooting Gmail slowness and determining why Gmail is slow. 

If these measures fail to reveal the root problem, conduct the tests and analyses described below.

Run a ping test against Google mail servers

A ping test calculates the approximate time it takes for a small message to make a round trip to and from the server.

1. Conduct this test:
   • In Windows:
     1. Open a command prompt.
     2. Click Start and then Run.
     3. Type ‘cmd’ and press Enter.
     4. At the prompt, enter the following command and press Enter:
        ping -s 10 mail.google.com
   • In OSX (Mac) and Linux:
     1. Open a terminal. On a Mac, search for ‘Terminal’ in the Spotlight search or find it under Applications.
     2. At the prompt, enter the following command and press Enter:
        ping -c 10 mail.google.com
2. Interpret the Google mail server ping test results:
   1. Check for packet loss. At the bottom of the ping result, you will see "X% packet loss". In general, any amount of packet loss indicates a problem in the route between you and the Gmail server.
   2. Check for long round trip times. At the bottom of the ping result, you will see "round-trip min/avg...". In general, the average round-trip time should not be greater than .05 seconds (50 milliseconds). If the round-trip time is greater than 500 ms, it signifies network issues that need to be investigated. Proceed to the traceroute test.

Run a traceroute test against Google mail servers

Run a traceroute test against Google mail servers if the ping test shows a round-trip time of greater than 50 ms or if there is any amount of packet loss. This test shows the route the packets take and helps identify the network routers experiencing delays.

1. Conduct this test:
   • In Windows:
     1. Open a command prompt.
     2. Click Start and then Run.
     3. Type ‘cmd’ and press Enter.
     4. At the prompt, enter the following command and press Enter:
        tracert mail.google.com
   • In OSX (Mac) and Linux:
     1. Open a terminal.
     2. At the prompt, enter the following command and press Enter:
        traceroute mail.google.com
2. Interpret the Google mail server traceroute results. Look for a circuitous route, lengthy hops, and connection drops:
   1. Check for long round trip times. Examine each line and ensure none exceeds 3 seconds (3,000ms). Here are example results indicating excessive latency:
      11  ppp-151-164-39-20.rcsntx.swbell.net (151.164.39.20) 9100.287 ms  8100.077 ms  9100.065 ms
      Run the traceroute command a few more times to make sure that the issue with the hop/host in question is persistent.
   2. Check for large numbers of hops. In general, barring a network routing issue, a path between a client and an end server should not exceed 20 or 25 hops. If you see traceroute output greater than 20 or 25 hops, please re-run the test to confirm the behavior. Then check your local network environment for any issues that may cause excessive hops. Proceed to the DNS ping test.

Run a ping test to your internal DNS server

Google determines users' locations by looking at where the associated DNS requests are coming from and then sends them to the closest Google servers for improved performance. If the users are using a nameserver in a different geographic location, Google is likely sending them to distant servers. By pinging your local DNS server, you can find out how far you are from it.

1. Conduct this test:
   • In Windows:
     1. Open a command prompt.
     2. Click Start and then Run.
     3. Type ‘cmd’ and press Enter.
     4. At the prompt, enter the following command and press Enter:
        ipconfig /all
     5. In the resulting connection information output, look for the ‘DNS Servers’ section and identify the IP address of the DNS server being used.
     6. Conduct a ping test as you did against Google mail servers but replace mail.google.com with the numeric IP address of your nameserver.
   • In OSX (Mac) and Linux:
     1. Open a terminal.
     2. At the prompt, enter the following command and press Enter:
        cat /etc/resolv.conf
     3. Note the first IP address that’s listed as a nameserver.
     4. Conduct a ping test as you did against Google mail servers but replace mail.google.com with the numeric IP address of your nameserver.
2. Interpret your DNS server ping test results:
   • When you ping the local DNS server, the duration shouldn't be more than 10 to 30 ms. In most networks, the value is less than 2 ms. If your result is more than that, a VPN or other internal enterprise network may be routing the users' traffic to another city. In this case, accessing Gmail can be slow. We recommend you contact your network administrator to see how latency to DNS could be reduced. This may entail network-level changes or something as simple as configuring user machines to access different DNS servers.
3. If your issue remains unresolved, contact Google Enterprise Support for additional assistance.